These studies have been concerned with a number of human pulmonary diseases of possible environmental origin, which are treated clinically by bronchoalveolar lavage. The diseases being studied are alveolar proteinosis, bronchial asthma, and some occupationally related unnamed pulmonary disorders. At present, attention has been directed towards characterization of lavage effluent components from patients with alveolar proteinosis, a human pulmonary disease of unknown etiology characterized by the accumulation of large amounts of proteinaceous material in the acini of the lungs.